AQA · A-Level · Chemistry

    Course version: 7405 · Version from Sept 2016

    Electronegativity as the power of an atom to attract the pair of electrons…

    Full specification wording

    Bond polarity: Electronegativity as the power of an atom to attract the pair of electrons in a covalent bond.

    Electronegativity is the power of an atom to attract the pair of electrons in a covalent bond towards itself.

    Checked against the AQA 7405 specification (opens in a new tab) on .

    • Point 1 of 4

    Study notes

    From the checked teaching notes for this specification point.

    The idea

    Electronegativity is the power of an atom to attract the pair of electrons in a covalent bond towards itself. It is measured on the Pauling scale, where fluorine is the highest at 4.0, followed by oxygen at 3.5, then nitrogen and chlorine at 3.0. Across a period it rises because nuclear charge increases while the bonding electrons stay in the same shell with similar shielding, so they are pulled in harder. Down a group it falls because the bonding pair lies in a shell further from the nucleus and is shielded by more inner shells. Only the shared pair is involved; the term says nothing about an atom's attraction for electrons in general.

    What earns the marks

    • The power or ability of an atom to attract electrons.
    • Specifying the pair of electrons in a covalent bond rather than electrons in general.
    • Explaining the trend using increasing nuclear charge and decreasing atomic radius.
    • Identifying the more electronegative atom correctly from supplied data.

    Common mistakes and how to put them right

    • Defining it as the attraction of an atom for all electrons rather than for a shared pair.

    • Applying the term to ions instead of to atoms joined by a covalent bond.

    • Claiming electronegativity increases down a group.

    • Confusing electronegativity with ionisation energy or electron affinity.

    Exam tips

    • Include the words bonding pair or pair of electrons in a covalent bond in your definition.
    • Use the data booklet values rather than memory when a question asks you to compare atoms.
    • Explain trends with nuclear charge, radius and shielding, the same three factors as ionisation energy.

    Try the lesson

    The start of the Bond polarity: Electronegativity as the power of an atom to attract the pair of electrons in a covalent bond. lesson, made from checked teaching notes for this specification point.

    Have a go first

    Which statement best defines electronegativity?

    Listen

    Electronegativity is the power of an atom to attract the pair of electrons in a covalent bond towards itself. It is measured on the Pauling scale, where fluorine is the highest at 4.0, followed by oxygen at 3.5, then nitrogen and chlorine at 3.0. Across a period it rises because nuclear charge increases while the bonding electrons stay in the same shell with similar shielding, so they are pulled in harder. Down a group it falls because the bonding pair lies in a shell further from the nucleus and is shielded by more inner shells. Only the shared pair is involved; the term says nothing about an atom's attraction for electrons in general. A strong answer earns marks for these points. the power or ability of an atom to attract electrons. specifying the pair of electrons in a covalent bond rather than electrons in general. explaining the trend using increasing nuclear charge and decreasing atomic radius. identifying the more electronegative atom correctly from supplied data. Exam tip: Include the words bonding pair or pair of electrons in a covalent bond in your definition.

    See it

    A top-down flowchart. The top node gives the definition: electronegativity is the power of an atom to attract the pair of electrons in a covalent bond. From it two branches lead down. The left branch is labelled 'Across a period: rises', and from it two nodes lead to a shared node: 'Nuclear charge increases' and 'Bonding electrons stay in the same shell with similar shielding', both feeding into 'Electrons pulled in harder'. The right branch is labelled 'Down a group: falls', and from it two nodes lead down: 'Bonding pair lies in a shell further from the nucleus' and 'Shielded by more inner shells'.
    It shows the definition of electronegativity and the reasons it rises across a period and falls down a group.

    Label the diagram

    Some boxes have lost their names. Pick the right name for each number.

    The diagram again, with 3 boxes numbered instead of named. A top-down flowchart. The top node gives the definition: electronegativity is the power of an atom to attract the pair of electrons in a covalent bond. From it two branches lead down. The left branch is labelled 'Across a period: rises', and from it two nodes lead to a shared node: 'Nuclear charge increases' and 'Bonding electrons stay in the same shell with similar shielding', both feeding into 'Electrons pulled in harder'. The right branch is labelled 'Down a group: falls', and from it two nodes lead down: 'Bonding pair lies in a shell further from the nucleus' and 'Shielded by more inner shells'.
    • 1Box 1

    • 2Box 2

    • 3Box 3

    0 of 3 labelled

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